Hello,

I have a material with changing properties - 2 states. I want to optimize 3 geometric parameters so that the contrast ratio between these two states is maximal. Is it possible to somehow insert this into optimization? E.g. for the first state I need to optimize 4 parameters to get the highest transmission, and for the second state the lowest transmission.

# Optimization of geometrical parameters for two possible states with different material properties

**milos.jonic**#1

Using a nested parameter sweep in an optimization

How can I access the results of a nested parametersweep in the custom figure of merit script (for optimization)?

**fgomez**#2

Hi Milos,

It is possible to do something like this by using a **sweep nested inside the optimization** and creating your own figure of merit. In the nested sweep you run separate simulations for the two material states. **The figure of merit must be a number** calculated from the results of the two simulations. For instance, you could use the difference in transmission between the two states.

I have created a simple example of an AR layer to illustrate this: AR_twostate_optimization.fsp (238.7 KB)…

In the “AR structure” group you can set the thickness and material of the AR layer. I created two dielectric materials, “mat_state1” and “mat_state2”, as examples of two possible states for the layer. In the nested sweep you need to specify these states under parameters. For the results I chose the reflection measured above the structure.

In the optimization settings you need to create your own figure of merit, for example the difference between the two states: fom = R(1)-R(2).

Some useful KB links for optimization are the following:

Optimization

Custom optimization algorithms

Nested sweeps

For more sophisticated optimization you can use MATLAB via Lumerical’s automation API.

How can I access the results of a nested parametersweep in the custom figure of merit script (for optimization)?

**lrj18**#4

I’m also confusing with this problem. In sweep, there are two simulations, simulation for ‘mat_state1’ and ‘mat_state2’. Each simulation gives a reflection coefficient R. If I want to optimize the difference between these two R. How could I set the FOM. I find the fom=R(1)-R(2) is not used as Fiugre of merit in the setup—Fiugre of merit—yes part